1. Field of the Invention
The present invention relates generally to electro-optic materials and more particularly to optical switches utilizing electro-optic materials to provide switching by total internal reflection.
2. Description of the Related Art
Electro-optic materials are commonly used in optical devices that rely on refractive index changes to manipulate transmission of optical signals. For example, optical switches that operate on the principle of total internal reflection may utilize electro-optic material to selectively generate a refractive index interface in the presence of an electric field. When the electric field is present, the optical signal incident on the refractive index interface is reflected and when the field is turned off, the optical signal propagates without reflection.
The performance of such optical switches depends in large part on the index gradient across the refractive index interface. If the gradient is sharp and abrupt, the performance will be better than if the gradient is broad and fuzzy. Unfortunately, the tendency of electric fields to fringe makes it difficult to achieve an interface with an abrupt boundary. Proposed solutions have included permanently poling the electro-optic material in opposite directions on opposite sides of an interface. Application of an electric field on both sides of the interface affects the magnitudes of the poling differently so as to create a refractive index difference. Such devices, however, are complex and costly. Accordingly, there is a need for a simpler, less expensive solution.